@Marina your reply was a godsend.
Since we just got the Switch/Minecraft, I hadn't setup a Microsoft account. That seems to have made all the difference in the world. Have successfully played twice for an hour each time.
Second time I had to log back into the Microsoft account which was annoying but hopefully it'll keep us logged in if we stay under the same Nintendo Online account since that's not something that changes often.
Hoping that also helps Mojang track down the bug.
@everyone that still can't play, try using your Microsoft account (creating one if you need to) and use the https://aka.ms/remoteconnect login approach on the opening screen and report back. That helped me at least play the game right now.
Another user here on a Switch (purchased for Christmas). Was able to play for about 2-3 hours and now the game won't load a world. New world lasted about 15 minutes before the generic error comes up and kicks you out.
Is it possible to get an ETA on a fix for this?
Tried both physical / downloaded copies, checking for corrupt data, etc but seeing that this has been around since July 2019 (related issues show one started in August 2018) it's a little concerning how long this will render the game unplayable.
If there's anything more needed to help test patches/fixes/etc, please let me know. More than happy to help on that side. Have a web development background and would love to help.
@Lindsay sorry to hear!
Hoping we can hear from Mojang soon.